April 4 2007
Dirt on your DSLR’s sensor appears as an annoying dark mark in the same spot on all your photos. It is more apparent in light coloured parts of the image, such as blue sky or a white dress.
Don’t panic, the mark can easily be removed from photos using the clone tool in editing software, such as Photoshop. When one spot turns into two or more, it becomes a nuisance. Dust on the sensor is a problem with DLSRs as it can enter the camera whenever the lens is changed, and there are still DSLR cameras without self-cleaning sensors.
Try not to let dust in, so change lenses in a clean dust free environment and shelter the camera from any wind. Inevitably some dust will get inside the sensor chamber while the shutter operates.
Cleaning Camera Sensors
Change the lens indoors, where dust is less likely to get into the camera, and hold it with the lens throat pointing down and give the inside a quick blow with a hand operated blower. These blowers are readily available from photographic suppliers. They are the shape of a rubber bulb that you squeeze to create a gentle puff of air. Pressure packs of compressed air can be a bit too powerful for the insides of a camera.
Camera manufacturers usually recommend in their operating manuals to return the camera to a qualified service agent to clean dust from the sensor. Incorrect cleaning could damage the delicate sensor. If you disregard the manufacturer’s advice, use the sensor cleaning function to hold the shutter open for cleaning. Then hold the camera pointing downwards and use the rubber hand blower to create a gentle breeze to encourage any dust particles to fall off the sensor. This should get rid of most dust spots, although, it may take a few tries. To test, take a shot of a light subject such as a nice even blue sky.
If there are stubborn spots then you need to consider professional cleaning, as the next step requires a degree of skill and care. Use only solvents and cleaning swabs made specifically for digital photographic sensors. The solvents are manufactured to a high level of purity and are designed to evaporate completely, leaving no residue on the sensor. Then there are specialist applicators, or swabs, these come in individual sealed plastic bags to ensure that they are completely dust free. They come in sizes to suit different sizes and shapes of sensors. Naturally, read and follow the manufacturer’s usage instructions.
Generally, put a drop or two of solvent onto a clean swab and then caress the surface of your sensor with the swab. Do not press the swab onto the sensor; just let it glide across the surface. Part of the job of the solvent is to form a thin liquid film between the swab and the surface of the sensor to lubricate this gliding motion. The solvent also loosens the bond between the dust and the sensor, so that the sideways motion of the swab sweeps it off the sensor. Once again this may take several attempts. Do not use force or press the swab roughly onto the sensor or be tempted to try a more powerful solvent, as you risk permanently damaging your sensor and that is far worse than an annoying dust spot. If all the above does not work, then seek professional help.
This is a common tool in photo editing software for removing unwanted spots and blemishes. This article goes into its use in more detail Clone Tool Basics